do NOT, under ANY circumstances, mutter the following words, in any context, in any order, lest they be misconstrued
luggage + bomb
for instance, do not say "there IS NO bomb in my luggage." or "there IS a BOMB in my luggage."
the only time this would be OK is when, THERE REALLY TRULY IS A BOMB.
my "authorities" tell me this is sound etiquette advice.